Spark-plug.



H. M. SPENCER.

SPARK PLUG.

APPLICATION HLED 8.27, 1915.

Patented June 13, 1916.

Witnesses Attorneys the completcd plug.

HARRY MARVIN SPENCER, OF DUNMORE, PENNSYLVANIA.

SPARK-PLUG.

Specification of Letters Patent.

Patented June 13, 1916.

Application filed February 27, 1915. Serial No. 10,977.

To all whom it may concern:

Be it known that I, HARRY Mauvits SPEN- GER, a citizen of the United States, residing at Dunmore, in the county of Lackawanna and State of Pennsylvania, have invented a new and useful Spark-Plug, of which the following is a specification.

The present invention appertains to spark plugs, and aims to provide a novel and improved spark plug capable of withstanding hard and long usage, and which will remain effective for a considerably longer time than the ordinary spark plug.

This invention is an improvement over the spark plug disclosed in my co-pending application, Serial No. 810,226, filed January .3, 191

As a more specific object, the invention aims to provide unique means for assembling the insulator and shell or body, whereby the insulator will not be clamped within the shell. or body, as usual, and in order that the shell may give or expand and contract under the changes to which the plug is subjected, and which will eliminate the possible cracking or breaking of the insulator.

It is also an object of the invention to provide a spark plug embodying a unique assemblage of component parts, and 1mproved generally in its construction, to enhance the utility, etliciency, and life of the ilug.

\Vith the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed can be made within the scope of what is claimed without departing from the spirit of the invention.

The invention is illustrated in the accompanying drawing, wherein Figure l is a side elevation of the plug showing the step of fastening or anchoring the insulator within the body. Fig. 2

is a longitudinal section taken on the line 2 2 of [fig i. Fig. I) is a side elevation of Fig. 4 is a longitudinal-scction ol' the plug taken on the line tr-i of Fig. 2a

.the shell,

The construction of the finished plug will first be described, in order that a thorough understanding of the finished plug may be had, before the manner of assembling the insulator and shell or body is taken up.

The present spark plug embodies a metallic shell or body 1 having a longitudinal bore 2 extending therethrough, the upper or outer end portion of the bore 2 being contracted slightly, as at 3, and there being a square internal shoulder 4 adjacentthe contracted portion 3. The shoulder 4 faces downwardly or inwardly toward that end of the. shell 1 which enters the combustion chamber of the cylinder, it being understood that the shell or body 1 is adapted to be threaded into the plug aperture of a cylinder of an internal combustion engine, as usual. The shell 1 is provided between its ends and near its inner end with an inner annular groove or recess 5 which forms an enlargement of the bore 2.- The shoulder 4 faces the groove 5.

' "lhajnsulator 6 projects through and fits leiisely within the bore 2 of the shell 1 and has its ends protruding beyond the ends of the insulator 6 being preferably constructed of kaolin, although it may be constructed of any suitable insulating material. The insulator 6 is provided With an outer or upper reduced portion 7 projecting through the reduced end portion of the bore 2 and projecting beyond the shell 1, and the reduced portion 7 provides an upwardly or outwardly facing shoulder 8 cooperating with the shoulder dot the shell 1. A copper or other suitable compressible gasket 3) is disposed snugly between the shoulders 25 and to provide a cushion between the insulator and shell, whereby the insulator may be thrust outwardly or upwardly slightly relative to the shell Without danger of injuring the ing a gas tight joint. In other words, the gasket 9 receives the outward or upward pressure of the insulator and also serves to close the annular gap or space between the insulator and shell.

The insulator (i is provided within the shell 1 with an annular or peripheral groove or recess ill complementing or registering with the groove 53 of the shell and the shell 1 is provided immediately above the groove insulator, and form- 5 with a vent and sight aperture or duct 11 extending from the bore 2 to the exterior of the plug. The vent or duct 11 is disposed between the groove 5 and shoulder 3.

Disposed within the cooperating grooves or recesses 5 and 10 and inner end portions of the shell and insulator is a filling 12 in the form of a suitable metallic chemical compound which is originally of liquid or semi-liquid consistency, and which after being introduced between the shell or body 1 and insulator 6, sets or hardens and bakes so as to provide a locking ring or key embedded in both the shell and insulator, and holding the insulator properly in place within the shell. The filling or locking'ring 12 is preferably of such composition as to have the same coeificient of expansion as the insulator, or the filling may have a slightly greater coefficient of expansion than the insulator, whereby there will be no tendency for the filling in contracting, to crush the insulator, or to crack or break itself. The manner of introducing the filling will be taken u hereinafter.

The insu ator 6 is provided with a longitudinal bore 13 extending therethrough, the lower or inner end portion of the bore 13 is counter bored or enlarged, as at 14, to provide a recess or chamber for the central or insulated electrode, and to receive the gaseous fuel for assisting in the cleaning of the electrodes'and insulator. The inner or lower end of the insulator 6 pro ects beyond the inner or lower end of the shell 1, as at 15, and is arranged to be heated by the gaseous fuel when it explodes, so that soot and other foreign matter which becomes deposited upon the protruding end portion 15 of the insulator will be dried and pulverized so that it will fall away from the plug. Furthermore, the fuel in entering the charm her or recess 14 and being ignited therein will blow out of the chamber 14 and thereby assist in cleaning the soot, oil and other foreign matter from the electrodes.

The counter bore or recess 14 provides a downwardly facing shoulder 16 carried by the insulator, and the rod or central conductor 17 which extends through the bore 13 of the insulator, is provided with a head 18 below the shoulder 16, a copper or compressible gasket 19 being disposed between the head 18 and shoulder 16 to provide a cushion between the rod or conductor 17 and the insulator for cushioning the upward strain or draft transmitted to the rod 17 and to make a gas tight joint. The head 18 carries the central sparking electrode or 'terminal 20 which projects out of the counter'bore 14, and which cotiperates with the sparking electrode or terminal 21 carried by outer end portion of the insulator 6, and

base of the sleeve 22 is disposed adjacent the shell 1 and bears against a wool or similar washer 23 disposed between the shell 1 and sleeve 22. The margi a1 portion of the washer 23 is seated wi in a dished band 23 which receives or fits around the lower end or face of the sleeve 22, the band 23 being flexible and assisting in yieldably supporting the sleeve 22 upon the shell 1 and around the outer end of the insulator.

A cap or socket nut 24 is threaded upon the rod or stem 17 and is engaged over the upper or outer end, of the sleeve 22, a wool J or similar washer 25 being disposed between the nut 23 and sleeve.22 whereby there is no liability for the outer end of the sleeve to .become chipped or broken under the strains -nut 26 is not liable to injure the insulator. The nut 26 being tightened, will secure the rod or stem 17 to the insulator,

and the gasket 19 and washers 27 and 28 will provide cushions between the rod or stem 17 and the'insulator, whereby the insulator and the rod or stem may expand and contract relative to one another without the. liability of breaking ,or injuring the insulator, and whereby a gas tight joint is retained. v

A binding post nut 29 for the attachment of the electrical conductor is threaded upon the outer or upper end of the rod or stem 17.

In assembling the shell land the insulator 6, as suggested in Figs. 1 and 2, all the other parts of the plug are removed with the exception of the gasket 9, and a clamp- .ing or holding rod 30 is inserted through the insulator and is provided at its inner or lower ,end with a head 31, suitable washers 32 beinggdisposed between the head 31 and the inner or lower endof the insulator. A metal sleeve 33 is seated against the shell 1 and surrounds and protects the outer end portion of the insulator, and the outer end of the sleeve 33 is provided with an inturned flange or lip 34 against which a nut 35 seats. The nut 35 is threaded upon the outer end portion of the rod 30, and when the nut 35 is tightened, it will hold the. insulator in place within the body. Prior to the insertion of the insulator within the shell, the gasket 9 is applied upon the insulator. so as to be clamped between the shoulders 4 and 8 of the shell and insulator, respectively. The nut 35 is tightened sufficiently, to hold theinsulator firmly within the shell and against the compressed gasket 9. The filling or material 12 which is in a liquid or semiliquid state is then forced or run into the annular space between the inner end portions of the shell and insulator, and will flow into the grooves or recesses 5, the duct or aperture l1 providing a vent for the escape of the air when the filling is introduced. As soon as the filling reaches the vent or duct 11, the pouring of the filling is stopped, and the filling is then allowed to harden or set. 15 Then, the subsequent heating of the plug will cause the filling to assume the nature of sand stone, and as a result the insulator will be ellectively held within the shell a gas tight joint, but at the same time, the shell is free to expand and contract without subjecting the insulator to excessive strainsz, The rod and sleeve 33 are then removed, The insulator is held at only one point within the shell, and the present manner of 25 fastening the insulator Within the shell eliminates the use of an ordinary bushing nut, it being evident to those familiar in the art that the use of a bushing nut results in the clamping of the insulator within the body 3 or shell, and which not infrequently causes the insulator to break or crack. Those portions of the shell at the opposite sides of the locking ring or key provided by the filling 12 and thecorresponding portions of 35 the shell are free to expand and contract, and the gasket 9 is adapted to yield, and will assist the filling 12 in closing the space between the shell and insulator. The sleeve .2 protects the outer-end of the insulator, and

serves to finish off the exterior of the plug the shoulder and groove thereof.

in a neat and desirable manner, the rod or stem 17 may also fit loosely within the bore of the insulator, withoutdanger of leakage, since the gasket 10 and washers 27 and 28 will close the passage through the insulator,

and furthermore, the outer end portion of -th'e insulator is also inclosed by the sleeve 22 and accompanying parts to prevent leakage.

The present plug is used in the manner of an ordinary plug, which needs no lengthy description, and will have a long life.

The insulator body or shell may be readil v assembled 'in the manner depicted in Fig. 1 and above described, and after the filling 12 has set, the rod 30, nut ill and sleeve 33 may be removed so that the remaining parts of the plug may be readily assembled with the insulator and body.

The hollow or chambered portion 15 of the insulator which projects beyond the inner end of the shell, will lie in the flames within the cylinder when the explosion occurs. and as a result will become very hot. During the compression stroke, the bore or cavity 14, which in practice is one inch deep and 1 g of an inch in diameter, is filled with gas due to the compression of the gas, and the gas within the counter bore or chamber 14 will become highly superheated, and needs very little additional heat in order to become ignited. lhe prescnt insulator therefore provid s a perfect ignition at any speed of the engine, even when the magneto is rotated slowly and produces a cold spark l' mveen the terminals or electrodes 20 ass 21, as well as when the magneto is rotated rapidly to produce a hot spark. The charge of gas in the cylinder does not depend upon the electric spark directly for ignition, but is ignited by the flash from the gas which oc- 1 against A curs when the super-heated gas 1n the counter bore or cavltyl l is flash penetrates the charge of gas within the cylinder and produces a long flame which. will quickly and etlectively ignite the charge, and in a manner which is much superior to the ignition created by a mere spark between the electrodes or terminals.

Having thus described the invention, what is claimed as new is:

1. In a spark plug, a shell having an internal annular shoulderailjacent its outer end facing its inner electrode end, and an inner annular groove near its inner end, an insulator within the shell having a shoul der facing the aforesaid shoulder and a peripheral groove registering with the aforesaid groove, a compressed gasket fittin snugly between said shoulders, and a filling between said grooves forming an annular key embedded in botli the shell and insulator, the shell having a vent between ignited. This 2. A spark plug, including a metallic shell having an internal shoulder adjacent its outer end and facing the inner end, an insulator projecting through the shell and having a longitudinal bore, a counter bore at its inner end, and a shoulder iacing the first mentioned shoulder, a compressed gasket between said shoulders, the shell and insulator having complementing annular grooves near their inner ends, a composition filling in said grooves, a rod extending through the insulator bore and having a head adjacent the shoulder formed by the counter bore, and an electrode projecting from saidhead out of the counter bore, an electrode carried by the inner end of the shell and coiiperating with the aforesaid electrode, a compressible gasket between said head and third mentioned shoulder, a nut threaded upon said rod, :1 dished metallic washer under said nut, a compressible washer between said dished washer and outer end of the insulator, an insulating sleeve sun-minding the outer end portion of the insulator and projecting beyond the outer end thereof, a Washer between the shell and, sleeve, :1 dished hand in which the third mentioned washer is Seated and fitting around the inner eml 0f the sleeve, :1 cap nut threaded upon, the rod and engaging over the outer end of the sleeve, and a Washer between the said cap nut and sleeve.

In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence oftwo witnesses.

HARRY MARVIN SPENCER.

\Vitnesses:

C. H. SPENCER, THEODORE F. VILLIAMS 

